1. Field of the Invention
The present invention relates to a heavy oil emulsified fuel combustion apparatus of a heavy oil emulsified fuel combustion boiler and the like for a public utility or an industrial use.
2. Description of the Prior Art
FIG. 3 is a schematic diagram of a prior art heavy oil emulsified fuel combustion boiler. In the boiler shown in FIG. 3, a heavy oil emulsified fuel 101 is directly supplied to a burner of a boiler 10 from a fuel tank 100. An atomizing steam 9 for the heavy oil emulsified fuel 101 is also supplied to the burner so that the heavy oil emulsified fuel 101 is atomized to combustible particle sizes.
Then, the fuel 101 is burnt in the boiler 10. On the other hand, in order to blow off the ash content, etc., sticking to heat exchanger tubes, etc., in the boiler 10, other steam 8 is supplied into the boiler 10. A waste gas 11 generated by combustion in the boiler 10 flows through a denitration apparatus 20, a dust removal apparatus 30 and a desulfurization apparatus 40 and is discharged into the air from a stack 50.
In the prior art, the heavy oil emulsified fuel 101 is supplied to the boiler 10 at an ordinary temperature, but because there is approximately 20 to 30% water contained in the heavy oil emulsified fuel 101, heat is required for vaporizing the water in the boiler 10, with the result that the boiler efficiency is lowered.
In the prior art heavy oil emulsified fuel combustion boiler as aforementioned, the boiler efficiency lowers due to a large amount of water contained in the heavy oil emulsified fuel. Because a large amount of water is contained in the boiler waste gas, a sulfuric acid dew point is elevated, and thus there is a problem of corrosion generating at, and soot and dust sticking to, downstream equipment. This in turn results in a problem of an increase of the water amount used for a soot blowing, etc. for removing the sticking dust.
Also, there is a problem in that a combustion gas amount increases due to steam generated by the combustion of the heavy oil emulsified fuel, which results in the enlargement of the downstream equipment.
Accordingly, in order to solve these problems, as aforementioned, in the heavy oil emulsified fuel combustion apparatus, i.e. to preventing the combustion efficiency from lowering due to the water content in the fuel and by preventing the sulfuric acid dew point from elevating due to water content in the combustion waste gas, the inventors here have heretofore disclosed a heavy oil emulsified fuel combustion apparatus in which the heavy oil emulsified fuel is burnt after the water content thereof is removed.
In a dewatering operation of the heavy oil emulsified fuel, a pressure reduction is done from a high pressure to an ordinary pressure of the heavy oil emulsified fuel which is pressurized and heated, and in this pressure reduction, a large number of steam bubbles arises. Unless these bubbles are eliminated, they mix into the dewatered emulsified fuel side, so that they are condensed to become water when the heavy oil emulsified fuel has been cooled down, with the result that the dewatering efficiency is lowered.
Thus, it is necessary to eliminate the large number of steam bubbles which arise when the pressure reduction is done from the high pressure to the ordinary pressure in the dewatering operation of the heavy oil emulsified fuel and to separate the steam to a separated steam side.